Remove symlinks from git tracking and improve lexicons setup
- Remove lexicons/{app,chat,com,tools} symlinks from git tracking
- Add symlink paths to .gitignore (they'll be created during setup)
- Add setup script scripts/setup-lexicons.sh for easy initialization
- Update lexicons/README.md with detailed setup instructions
- Update main README.md with submodule initialization steps
This makes the repository cleaner by not tracking generated symlinks
while providing clear setup instructions for new contributors.